I don't know about other kernels but with ChevyNo1s kernel... Just saying this to be safe.

Download the kernel blablablabla.zip to the ROOT of your SD Card.
Go into Rom Manager and select 'Install ROM from SD Card'.
Go down the list of files till you find blablablabla.zip and Tap it
Don't Check Wipe Data but you can check Backup if you have not backed up in a while.